ML20217C865
| ML20217C865 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 07/01/1991 |
| From: | Clifford J Office of Nuclear Reactor Regulation |
| To: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| References | |
| TAC-77936, NUDOCS 9107180207 | |
| Download: ML20217C865 (5) | |
Text
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i July 1,1991 Docket Nos. 50-445 and 50-446 Mr. William J. Cahill, Jr.
Executive Vice President, Nuclear TU Electric Company 400 North Olive Street, L.B. 81 Dallas, Texas 75201
Dear Mr. Cahill:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION REGARDING TOPICAL REPORT RXE-89-602, "VIPRE-01 CORE THERMAL-HYDRAULIC ANALYSIS METHOD 5" (TAC NO. 77936)
During the review of the subject report, the NRC staf f has determined the need for additional information.
Enclosed is a list of questions from the NRC technical staff and our contractor.
if clarification of the questions is required by your staff, please contact me.
The reporting requirements contained in this letter af fect fewer than ten respondents; therefore, OMB clearance is not required under Public Law 96-511.
We request your response to the questions in the enclosure within 21 days of the receipt of this letter to enable the staff to complete its review in a timely manner.
Sincerely, Original Signed By Thomas A. Bergman hJamesW.Clifford,ProjectManager Project Directorate IV-2 Division of Reactor Projects - 111, IV, V Office of Nuclear Reactor Regulation
Enclosure:
Request for Additional Information cc w/ enclosure:
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Mr. William J. Cahill, Jr.,
cc:
Senior Resident inspector Jack R. Newman, Esq.
U.S. Nuclear Regulatory Commission Newman & Holtzinger l
P. O. Box 1029 1615 L Street, N.W.
Granbury, Texas 76048 Suite 1000 i
Regional Administrator, Region IV U.S. Nuclear Regulatory Comission Chief, Texas Bureau of Radiation Control 611 Ryan Plaza Drive, Suite 1000 Texas Department of Health Arlington, Texas 76011 1100 West 49th Street Austin, Texas 78756 Mrs. Juanita Ellis, President Citizens Association for Sound Energy Honorable Dale McPherson 1426 South Polk County Judge Dallas, Texas 75224 P.O. Box 851 Glen Rose, Texas 76043 Owen L. Thero, President Quality Technology Company Lakeview Mobile Home Park, Lot 35 4793 East Loop 820 South fort Worth, Texas 76119 Mr. Roger D. Walker Manager. Nuclear Licensing Texas Utilities Electric Company 400 North Olive Street, L.B. 81 Dallas, Texas 75201 Texas Utilities Electric Company c/o Bethesda Licensing 3 Metro Center Suite 610 Bethesda, Maryland 20814 William A. Burchette, Esq.
Counsel for Tex-La Electric Cooperative of Texas Jorden. Schulte1025ThomasJeffe&Burchette rson Street, N.W.
Washington, D.C.
20007 GDS Associates, Inc.
Suite 720 1850 Parkway Place Marietta, Georgia 30067-8237 t
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e ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION-ON RXE-89 002, "VIPRE 01 CORE THERMAL-HYDRAULIC ANALYS!$ METHODS FOR COMANCHE PEAK STEAM ELECTRIC STATION LICENSING APPLICATIONS 1.
State the " intended licensing applications" of TUEC's VIPRE 01 methodology.
Which input parameters does TUEC expect to have to change in " actual TV Electric licensing calculations"? Explain how these changes impact the validation analyses.
2.
Explain and justify the intended use for each of:
(1) the steady-state model designated as the " reference case"; and (ii) the CPSES VIPRE-01 model.
Explain which model will be used for licensing calculations.
3.
What is the DNB limiting transient for CPSES7 If it is other than the loss of flow transient, discuss and identify the impact that the limiting transient may have on the outcome of the sensitivity studies and selection of model options and inpLt parameters.
4 Provide a detailed description of and justify the data used for the following:
a.
active fuel length b.
the choice of a factor for core flow maldistribution c.
grid loss coefficient d.
uniform grid spacing e,
damping factor-f, gap / centroid distance 9
slip ratio h.
turbulent mixing coefficient, ABETA 1.
core bypass flow assumed j.
pitch reduction _ factor (Section 5.1)
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5.
Justify, by providing sensitivity study results, that the selection of the following parameters result in conservative and stable MDNBR prediction:
a.
convergence criteria b.
time step sizes 6.
Discuss how a hounding value for the gap conductance 1J determined on a transient specific basis.
7 TUEC uses a dummy rod model to represent the fuel rods for steady-state DNB analysis.
Explain how the rod surface heat flux is computed for input to the VipRE-01 model.
8.
Justify use of a 1/8 core symmetric base model to analyze asymmetric transients including the MSLB transient, provide a detailed discussion of how the MSLB DNBR calculations are performed.
9.
provide and justify that the data used for the following are conservative or provide references of prior approval of their use:
(i)hotchannel factor, (ii) axial power profile and its peaking f actor, (iii) radial peaking factor and pin radial-local peak, and (iv) engineering enthalpy rise hot channel factor.
10.
Discuss further ano justify not using an engineering heat flux hot channel # actor (Section 6.6).
Since not using this factor results in a 3% increase in the MDNBR, explain the statement "no additional DNBR penalty is required" to account for this effect.
Similarly, discuss and justify not using a hot channel pitch reduction factor which is worth 3%
in the predicted MDNBR.
11.
In the benchmark analyses TUEC used a constant value for some system parameters, such as inlet temperature and system pressure for the loss of e
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flow transient, obtained from the current FSAR.
Since in future licensing calculationt., TVEC intends to use RETRAN-02 to generate the boundary conditions, discuss, in-depth by providing comparison of a limiting transient case, the isnpact expected on the DNB calculatirns, the MDNBR and model option selections.
12.
Describe in detail how the DNBR penalty due to the rod bow effect will be determined and accounted.
13.
Do you intend to use VIPRE to calculate the hot leg boiling limit and steam generator safety valve lines for the core safety limits (Section A1.3)? If so, provide comparison between your VIPRE calculations and the FSAR calculations, l
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